Light control film (LCF), also known as light collimating film, is an optical film that is configured to regulate the directionality of transmitted light. Various LCFs are known, and typically include a light transmissive film having a plurality of parallel grooves wherein the grooves are formed of a light absorbing material. Depending on the orientation of the grooves, the pitch, and the geometry of the grooves (e.g., the side-wall angle), the LCF may provide for maximum transmission at a predetermined angle of incidence with respect to the image plane and provide for image cut-off or black-out along a given polar coordinate (e.g., horizontally in the case of so-called privacy filters, or vertically when such light control films are integrated into instrument panel displays for automobiles).
LCFs may be placed proximate a display surface, image surface, or other surface to be viewed. Typically, LCFs are designed such that at normal incidence, (i.e., 0 degree viewing angle, when a viewer is looking at an image through the LCF in a direction that is perpendicular to the film surface and image plane), the image is viewable. As the viewing angle increases, the amount of light transmitted through the LCF decreases until a viewing cutoff angle is reached where substantially all the light is blocked by the light-absorbing material and the image is no longer viewable. When used as a so-called privacy filter (for instance, for liquid crystal displays in computer monitors or laptop displays), this characteristic of LCFs can provide privacy to a viewer by blocking observation by others that are outside a typical range of viewing angles.
LCFs can be prepared, for instance, by molding and ultraviolet curing a polymerizable resin on a polycarbonate substrate. Such LCFs are commercially available from 3M Company, St. Paul, Minn., under the trade designation “3M™ Filters for Notebook Computers and LCD Monitors”.
Color shifting films are multilayered polymeric films, such as described in U.S. Pat. No. 6,531,230.